Trade union membership has increased for the first time in years – up by 59,000 to 6.5m, new figures have shown.
The rise last year follows four consecutive annual falls in membership of more than 100,000 after a period of broad stability between 1995 and 2007.
Trade union membership levels have kept pace with an increase in the numbers of workers between 2011 and 2012, remaining at 26%.
TUC general secretary Frances O'Grady said: "We are pleased that membership has increased over the last year, especially given high unemployment and swingeing government cuts.
"This shows that staff, both in the public and private sector, know that a union membership card is still the best guarantee of skills training, job security and fairness at work.
"Unions have played a key role in exposing the impact of the government's self-defeating austerity programme and we will be stepping up our campaign for investment in jobs and growth for the future."
The latest figure compares with a peak of over 13m union members in 1979.